Wells are drilled into the earth's crust using a drilling rig. Tubular strings are lengthened by threadably coupling add-on tubular segments to the proximal end of the tubular string. The tubular string is generally suspended within the borehole using a rig floor-mounted spider as each new tubular segment or stand is coupled to the proximal, end of the tubular string just above the spider. A single joint elevator is used to grip and secure the segment or stand to a hoist to lift the segment or stand into position for threadably coupling to the tubular string.
For installing a string of casing, existing single joint elevators generally comprise a pair of hinged body halves that open to receive a tubular segment and close to secure the tubular within the elevator. Elevators are specifically adapted for securing and lifting tubular segments having conventional connections. A conventional connection comprises an internally threaded sleeve that receives and secures an externally threaded end from each of two tubular segments to secure the segments in a generally abutting relationship. The internally threaded sleeve is first threaded onto the end of a first tubular segment to form a “box end.” The externally threaded “pin end” of the second tubular segment is threaded into the box end to complete the connection between the segments. Typical single joint elevators have a circumferential shoulder that forms a circle upon closure of the hinged body halves. The shoulder of the elevator engages the tubular segment under a shoulder formed by the end of the sleeve and the tubular segment. However, conventional single joint elevators cannot grip a tubular segment having integral connections, because an integral connection has no sleeve to form a circumferential shoulder.
What is needed is a single joint elevator that is securable to a tubular at any position along the length of the tubular segment, and not only at the sleeve. What is needed is a versatile single joint elevator that can automatically and positively open and close about a tubular segment having either integral connections or conventional connections.